Forum: GNU Radio Very low packet loss rate for the discontinuous BPSK communications- the analysis and looking for so

Hello,

In the current gr-digital/narrowband, I am using the benchmark_tx.py and
rx.py to test the bpsk communications.
It is found that the packet loss rate is very high (70% loss) in
discontinuous mode where every 5 packets are in a burst. But in 
continuous
mode, the paket loss rate is less than 10% for the same point to point
link.

I captured the waveform data. From the observed result, it seems that 
for
each burst (5 packet), the bpsk receiver needs to re-do the 
frequency/time
sync. This will directly causes that the first packet of each burst will
definitely be crashed. Also, some burst can not be demodulated correctly 
at
all. For the same reason, even in the continuous mode, the very first
packet is also crashed at the receiver.

I have tried  to add very long preamble for each packet to ensure the 
data
part of the packet can be received in well sync status. But the result 
is
not very good.

Before I get further investigation on the solutions, just wondering if 
any
ideas or existing work within this community.

--

Alex,
*Dreams can come true  just believe.*

Seems no one can shed a light on this topic?


On Thu, Feb 28, 2013 at 10:25 PM, Alex Zhang 
<cingular.alex@gmail.com>wrote:

> each burst (5 packet), the bpsk receiver needs to re-do the frequency/time
> ideas or existing work within this community.
>
> --
>
> Alex,
> *Dreams can come true  just believe.*
>



--

Alex,
*Dreams can come true  just believe.*